How do you impose a character limit on a text input in HTML?
In addition to the above, I would like to point out that client-side validation (HTML code, javascript, etc.) is never enough. Also check the length server-side, or just don't check at all (if it's not so important that people can be allowed to get around it, then it's not important enough to really warrant any steps to prevent that, either).
Also, fellows, he (or she) said HTML, not XHTML. ;)